Some early studies found marijuana to have positive effects, sexually, for men. For instance, in a 1982 survey 75% of men reported sexual enhancement from smoking marijuana (…love weed, baby). But a study published last year in the journal European Urology found the penis to contain receptors for tetrahydrocannabinol (THC), the active ingredient in the Mary Jane. The receptors are located mainly throughout the smooth muscle of the penis. Additional lab studies suggest that THC has an inhibitory effect on the muscle.

Says Shamloul, “This is a more serious effect on the erectile function because the smooth muscle makes up 70 percent to 80 percent of the penis itself.”

As Shamloul says, many of the older studies showing marijuana to have positive effects on sexual performance are flawed in their lack of controlling for perceptual alterations caused by the THC itself. Other studies from the same year showed male marijuana smokers to have twice the rate of erectile dysfunction as non-smokers. Another study showed the effects of marijuana on sexual function to be dose specific–small doses having positive effects and larger doses working in the negative.

“What we are really missing are clinical studies,” Shamloul said. “We are stuck with only animal studies and molecular studies, and some clinical studies done in the ’60s and ’70s, most on a very small number of men… We need well-designed, placebo-control studies examining marijuana’s effect in both the short-term and long-term.”

Yeah im not gonna uss my name but swim hopes this helps someone. Swims been using marijuana for years and recently swim took a sobriety break for 2 weeks after years. Swim had way better sexual preformance than recently when swim smoked again. Swim gets a erection but cannot keep one after ejaculation which is much sooner with having recently smoked. Swim has noticed by reducing use that it takes 48 hrs sober for swims penis to work. I sit there and want to fuck and wish swim never toked up. Every one is differnet but swim has to quit marijuana.